Abstract: The development of the virtual assembly system oriented to education and training usually involves similar tasks, multiple training modes and many terminals, which are usually customized. In order to improve the efficiency and universality of development, the common elements of virtual assembly operations are summarized and a parametric model that includes task elements, static elements and action elements is proposed to describe the assembly operation process. A parametric presentation method based on XML is designed. The recognition mechanism of assembly operation-interactive intention is studied. Based on it, the logical expression and analysis of the three training modes of demonstration, practice and examination is realized. The example for a reducer virtual assembly shows that the parametric presentation method based on XML can improve the efficiency of virtual assembly system development.